(1) Field of the Invention
This invention relates to an organic electroluminescent element and a method of repairing the same.
(2) Description of the Related Art
FIGS. 7 and 8 illustrate an example of a simple matrix drive-type conventional electroluminescent display unit employing an organic electroluminescent element, wherein FIG. 7 illustrates a schematic structure of the conventional electroluminescent display unit and FIG. 8 illustrates an arrangement of transparent electrodes and metal electrodes.
As shown in FIGS. 7 and 8, a plurality of transparent electrodes 2 made of indium tin oxide (hereinafter, ITO) are arranged in parallel with each other on a transparent board 1, on which an organic material layer 3 is formed and on the organic material layer 3, a plurality of metal electrodes 4 are arranged in parallel with each other in such a relation as to be at right angles to the transparent electrodes 2.
When a current or a voltage is applied between the transparent electrodes 2 and the metal electrodes 4 (see FIG. 8), a current flows through the organic material layer 3 between the transparent electrodes 2 and the metal electrodes 4, to which the current or the voltage is applied, arranged orthogonally with each other, thereby resulting in luminescence.
The organic material layer 3 and the metal electrodes 4 are formed by depositing respective materials by using an evaporation method and the like after the transparent electrodes 2 are formed on the transparent board 1.
At this time, as shown in FIG. 9, when a dirt 10 adheres onto the transparent electrode 2, evaporated molecules of the organic material are scarcely deposited onto spot indicated by arrow A in the figure situated in the shadow of the dirt 10, causing the organic material layer 3 in the vicinity of the spot to become thin.
As a result, a distance between the transparent electrode 2 and the metal electrode 4 in the vicinity of the spot decreases, decreasing a electrical resistance therebetween and resulting in a current leak caused by an excess concentration of a current, further causing a failure in luminescence and that in an electroluminescent element.
It is therefore an objective of the present invention to solve the above problem of a failure in luminescence and a failure in an electroluminescent element caused by the current leak and to provide an organic electroluminescent element and a method of repairing the same.
In order to attain the above objective, a first aspect of the present invention is to provide an organic electroluminescent element including transparent electrodes, a plurality of organic material layers and metal electrodes being formed in order on a transparent board, comprising a protective layer for preventing current leak formed between the transparent board and a plurality of the organic material layers, wherein the protective layer for preventing current leak and/or a part of a plurality of the organic material layers is evaporated by absorbing an irradiated laser beam.
A second aspect of the present invention is to provide a method of repairing an organic electroluminescent element including transparent electrodes, a plurality of organic material layers and metal electrodes being formed in order on a transparent board and comprising a protective layer for preventing current leak formed between the transparent board and a plurality of the organic material layers, characterized in that a laser beam, having substantially the same wavelength as an absorption wavelength of a material of the protective layer for preventing current leak and/or an organic material which forms a specific organic material layer from among a plurality of the organic material layers, is irradiated onto the protective layer for preventing current leak and/or the specific organic material layer so as to evaporate the protective layer for preventing current leak and/or the specific organic material layer.
The laser beam is irradiated from the transparent board side and absorbed by the specific organic material layer that is in contact with the transparent electrodes.